best pupil; leading disciple
Refers to the most outstanding or senior student of a teacher, master, or school, often in traditional arts, martial arts, or academic lineages.
He is known as the master's best pupil.
The leading disciples of that school gathered and gave a commemorative performance.
Compound of 高 (high, noble) and 弟 (younger brother, pupil). The exact historical derivation is uncertain, but the kanji combination conventionally conveys the meaning of a distinguished or foremost disciple.